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Wu S, Tong X, Peng C, Luo J, Zhang C, Lu K, Li C, Ding X, Duan X, Lu Y, Hu H, Tan D, Dai F. The BTB-ZF gene Bm-mamo regulates pigmentation in silkworm caterpillars. eLife 2024; 12:RP90795. [PMID: 38587455 PMCID: PMC11001300 DOI: 10.7554/elife.90795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024] Open
Abstract
The color pattern of insects is one of the most diverse adaptive evolutionary phenotypes. However, the molecular regulation of this color pattern is not fully understood. In this study, we found that the transcription factor Bm-mamo is responsible for black dilute (bd) allele mutations in the silkworm. Bm-mamo belongs to the BTB zinc finger family and is orthologous to mamo in Drosophila melanogaster. This gene has a conserved function in gamete production in Drosophila and silkworms and has evolved a pleiotropic function in the regulation of color patterns in caterpillars. Using RNAi and clustered regularly interspaced short palindromic repeats (CRISPR) technology, we showed that Bm-mamo is a repressor of dark melanin patterns in the larval epidermis. Using in vitro binding assays and gene expression profiling in wild-type and mutant larvae, we also showed that Bm-mamo likely regulates the expression of related pigment synthesis and cuticular protein genes in a coordinated manner to mediate its role in color pattern formation. This mechanism is consistent with the dual role of this transcription factor in regulating both the structure and shape of the cuticle and the pigments that are embedded within it. This study provides new insight into the regulation of color patterns as well as into the construction of more complex epidermal features in some insects.
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Affiliation(s)
- Songyuan Wu
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
| | - Xiaoling Tong
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
| | - Chenxing Peng
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
| | - Jiangwen Luo
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
| | - Chenghao Zhang
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
| | - Kunpeng Lu
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
| | - Chunlin Li
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
| | - Xin Ding
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
| | - Xiaohui Duan
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
| | - Yaru Lu
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
| | - Hai Hu
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
| | - Duan Tan
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
| | - Fangyin Dai
- State Key Laboratory of Resource Insects, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Sericulture, Textile and Biomass Sciences, Southwest UniversityChongqingChina
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Figon F, Casas J. Ommochromes in invertebrates: biochemistry and cell biology. Biol Rev Camb Philos Soc 2019; 94:156-183. [PMID: 29989284 DOI: 10.1111/brv.12441] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 06/09/2018] [Accepted: 06/12/2018] [Indexed: 01/24/2023]
Abstract
Ommochromes are widely occurring coloured molecules of invertebrates, arising from tryptophan catabolism through the so-called Tryptophan → Ommochrome pathway. They are mainly known to mediate compound eye vision, as well as reversible and irreversible colour patterning. Ommochromes might also be involved in cell homeostasis by detoxifying free tryptophan and buffering oxidative stress. These biological functions are directly linked to their unique chromophore, the phenoxazine/phenothiazine system. The most recent reviews on ommochrome biochemistry were published more than 30 years ago, since when new results on the enzymes of the ommochrome pathway, on ommochrome photochemistry as well as on their antiradical capacities have been obtained. Ommochromasomes are the organelles where ommochromes are synthesised and stored. Hence, they play an important role in mediating ommochrome functions. Ommochromasomes are part of the lysosome-related organelles (LROs) family, which includes other pigmented organelles such as vertebrate melanosomes. Ommochromasomes are unique because they are the only LRO for which a recycling process during reversible colour change has been described. Herein, we provide an update on ommochrome biochemistry, photoreactivity and antiradical capacities to explain their diversity and behaviour both in vivo and in vitro. We also highlight new biochemical techniques, such as quantum chemistry, metabolomics and crystallography, which could lead to major advances in their chemical and functional characterisation. We then focus on ommochromasome structure and formation by drawing parallels with the well-characterised melanosomes of vertebrates. The biochemical, genetic, cellular and microscopic tools that have been applied to melanosomes should provide important information on the ommochromasome life cycle. We propose LRO-based models for ommochromasome biogenesis and recycling that could be tested in the future. Using the context of insect compound eyes, we finally emphasise the importance of an integrated approach in understanding the biological functions of ommochromes.
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Affiliation(s)
- Florent Figon
- Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Université de Tours, 37200 Tours, France
| | - Jérôme Casas
- Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Université de Tours, 37200 Tours, France
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Fujii T, Yamamoto K, Banno Y. Translucent larval integument and flaccid paralysis caused by genome editing in a gene governing molybdenum cofactor biosynthesis in Bombyx mori. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 99:11-16. [PMID: 29803701 DOI: 10.1016/j.ibmb.2018.04.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 04/28/2018] [Accepted: 04/28/2018] [Indexed: 06/08/2023]
Abstract
Translucency of the larval integument in Bombyx mori is caused by a lack of uric acid in the epidermis. Hime'nichi translucent (ohi) is a unique mutation causing intermediate translucency of the larval integument and male-specific flaccid paralysis. To determine the gene associated with the ohi mutation, the ohi locus was mapped to a 400-kb region containing 29 predicted genes. Among the genes in this region, we focused on Bombyx homolog of mammalian Gephyrin (BmGphn), which regulates molybdenum cofactor (MoCo) biosynthesis, because MoCo is indispensable for the activity of xanthine dehydrogenase (XDH), a key enzyme in uric acid biosynthesis. The translucent integument of ohi larvae turned opaque after injection of bovine xanthine oxidase, which is a mammalian equivalent to XDH, indicating that XDH activity is defective in ohi larvae. RT-PCR and sequencing analysis showed that (i) in ohi larvae, expression of the BmGphn gene was repressed in the fat body where uric acid is synthesized, and (ii) there was no amino acid substitution in the ohi mutant allele. Finally, we obtained BmGphn knockout alleles (hereafter denoted as BmGphnΔ) by using CRISPR/Cas9. The resulting ohi/BmGphnΔ larvae had translucent integuments, demonstrating that BmGphn is the gene responsible for the ohi phenotype. Our results show that repressed expression of BmGphn is a causative factor for the defective MoCo biosynthesis and XDH activity observed in ohi larvae. Interestingly, all male BmGphnΔ homozygotes died before pupation and showed a flaccid paralysis phenotype. The genetic and physiological mechanisms underlying this flaccid paralysis phenotype are also discussed.
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Affiliation(s)
- Tsuguru Fujii
- Laboratory of Silkworm Genetic Resources, Institute of Genetic Resources, Graduate School of Bio Resources and Bioenvironmental Science, Kyushu University, Fukuoka, 812-8581, Japan
| | - Kazunori Yamamoto
- Laboratory of Silkworm Genetic Resources, Institute of Genetic Resources, Graduate School of Bio Resources and Bioenvironmental Science, Kyushu University, Fukuoka, 812-8581, Japan
| | - Yutaka Banno
- Laboratory of Silkworm Genetic Resources, Institute of Genetic Resources, Graduate School of Bio Resources and Bioenvironmental Science, Kyushu University, Fukuoka, 812-8581, Japan.
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Zhang H, Lin Y, Shen G, Tan X, Lei C, Long W, Liu H, Zhang Y, Xu Y, Wu J, Gu J, Xia Q, Zhao P. Pigmentary analysis of eggs of the silkworm Bombyx mori. JOURNAL OF INSECT PHYSIOLOGY 2017; 101:142-150. [PMID: 28750999 DOI: 10.1016/j.jinsphys.2017.07.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 06/21/2017] [Accepted: 07/23/2017] [Indexed: 06/07/2023]
Abstract
Ommochromes are major pigments involved in coloration of eggs, eyes, wings, and epidermis of insects. Bombyx mori (silkworm) eggs contain a mixture of ommochrome pigments and their precursors. Here, we analyzed the pigment composition of every egg color strain using egg color mutants (w-2, pe, and re) and wild-type strains (dazao and C108) by using full wavelength scanning and high-performance liquid chromatography. We identified ommochrome pigments and their precursors in pigment extracts from non-diapause eggs and diapause eggs, and found that the quantities of ommochrome precursor 3-hydroxy-kynurenine were much higher in the diapause eggs. Ommochrome pigments were absent in the non-diapause eggs. We analyzed the pigment composition of every egg color strain and found an accumulation of 3-hydroxy-kynurenine and absence of ommochromes in the yellow eggs (w-2 and pe), suggesting that the essential factors for ommochrome biosynthesis are high levels of 3-hydroxy-kynurenine, enzymes for ommochrome synthesis and transferase, and spermatiation. Moreover, we confirmed that both decarboxylated xanthommatin and xanthommatin are major ommochrome pigments, and the quantity of decarboxylated xanthommatin is much higher than that of xanthommatin in silkworm eggs. Since ommochrome pigments can change color under oxidative/reductive conditions and the egg color mutant re turns crimson when preserved at a low temperature for a few weeks, we used an oxidation-reduction reaction in vitro to explore mechanisms behind the pigment-based color change. Specifically, during diapause, the contents of decarboxylated xanthommatin and xanthommatin are increased, and the ommochrome pigments convert into their reduced forms.
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Affiliation(s)
- Haiyan Zhang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Ying Lin
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Engineering and Technology Research Center for Novel Silk Materials, Chongqing 400716, China
| | - Guanwang Shen
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Engineering and Technology Research Center for Novel Silk Materials, Chongqing 400716, China
| | - Xue Tan
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Chao Lei
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Wei Long
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Hongling Liu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Yandi Zhang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Yinying Xu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Jinxin Wu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Jianjian Gu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Qingyou Xia
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Engineering and Technology Research Center for Novel Silk Materials, Chongqing 400716, China
| | - Ping Zhao
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Engineering and Technology Research Center for Novel Silk Materials, Chongqing 400716, China.
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Genetic Basis of Melanin Pigmentation in Butterfly Wings. Genetics 2017; 205:1537-1550. [PMID: 28193726 DOI: 10.1534/genetics.116.196451] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 02/06/2017] [Indexed: 11/18/2022] Open
Abstract
Despite the variety, prominence, and adaptive significance of butterfly wing patterns, surprisingly little is known about the genetic basis of wing color diversity. Even though there is intense interest in wing pattern evolution and development, the technical challenge of genetically manipulating butterflies has slowed efforts to functionally characterize color pattern development genes. To identify candidate wing pigmentation genes, we used RNA sequencing to characterize transcription across multiple stages of butterfly wing development, and between different color pattern elements, in the painted lady butterfly Vanessa cardui This allowed us to pinpoint genes specifically associated with red and black pigment patterns. To test the functions of a subset of genes associated with presumptive melanin pigmentation, we used clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 genome editing in four different butterfly genera. pale, Ddc, and yellow knockouts displayed reduction of melanin pigmentation, consistent with previous findings in other insects. Interestingly, however, yellow-d, ebony, and black knockouts revealed that these genes have localized effects on tuning the color of red, brown, and ochre pattern elements. These results point to previously undescribed mechanisms for modulating the color of specific wing pattern elements in butterflies, and provide an expanded portrait of the insect melanin pathway.
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Fujiwara H, Nishikawa H. Functional analysis of genes involved in color pattern formation in Lepidoptera. CURRENT OPINION IN INSECT SCIENCE 2016; 17:16-23. [PMID: 27720069 DOI: 10.1016/j.cois.2016.05.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 05/20/2016] [Accepted: 05/20/2016] [Indexed: 05/22/2023]
Abstract
In addition to the genome editing technology, novel functional analyses using electroporation are powerful tools to reveal the gene function in the color pattern formation. Using these methods, several genes involved in various larval color pattern formation are clarified in the silkworm Bombyx mori and some Papilio species. Furthermore, the coloration pattern mechanism underlying the longtime mystery of female-limited Batesian mimicry of Papilio polytes has been recently revealed. This review presents the recent progress on the molecular mechanisms and evolutionary process of coloration patterns contributing to various mimicry in Lepidoptera, especially focusing on the gene function in the silkworm and Papilio species.
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Affiliation(s)
- Haruhiko Fujiwara
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8562, Japan.
| | - Hideki Nishikawa
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8562, Japan
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Comparative analysis of the integument transcriptomes of the black dilute mutant and the wild-type silkworm Bombyx mori. Sci Rep 2016; 6:26114. [PMID: 27193628 PMCID: PMC4872147 DOI: 10.1038/srep26114] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 04/27/2016] [Indexed: 11/21/2022] Open
Abstract
The insect cuticle is a critical protective shell that is composed predominantly of chitin and various cuticular proteins and pigments. Indeed, insects often change their surface pigment patterns in response to selective pressures, such as threats from predators, sexual selection and environmental changes. However, the molecular mechanisms underlying the construction of the epidermis and its pigmentation patterns are not fully understood. Among Lepidoptera, the silkworm is a favorable model for color pattern research. The black dilute (bd) mutant of silkworm is the result of a spontaneous mutation; the larval body color is notably melanized. We performed integument transcriptome sequencing of the wild-type strain Dazao and the mutant strains +/bd and bd/bd. In these experiments, during an early stage of the fourth molt, a stage at which approximately 51% of genes were expressed genome wide (RPKM ≥1) in each strain. A total of 254 novel transcripts were characterized using Cuffcompare and BLAST analyses. Comparison of the transcriptome data revealed 28 differentially expressed genes (DEGs) that may contribute to bd larval melanism, including 15 cuticular protein genes that were remarkably highly expressed in the bd/bd mutant. We suggest that these significantly up-regulated cuticular proteins may promote melanism in silkworm larvae.
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Yuasa M, Kiuchi T, Banno Y, Katsuma S, Shimada T. Identification of the silkworm quail gene reveals a crucial role of a receptor guanylyl cyclase in larval pigmentation. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2016; 68:33-40. [PMID: 26561270 DOI: 10.1016/j.ibmb.2015.10.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 10/28/2015] [Accepted: 10/28/2015] [Indexed: 06/05/2023]
Abstract
Diverse color patterns on the integument of lepidopteran larvae play important roles in their survival through camouflage, mimicry, sexual signaling, and aposematism. In the silkworm Bombyx mori, many color pattern variations have been preserved in inbred strains making them a good model for elucidating the molecular mechanisms that underlie color pattern formation. In this study, we focused on the silkworm quail (q) mutant, which exhibits abnormalities in multiple pigment biosynthesis pathways. Positional cloning of the q gene revealed that disruption of a guanylyl cyclase gene, BmGC-I, is responsible for its abnormal pigmentation. In q mutants, we identified a 16-bp deletion in the BmGC-I transcript, resulting in the production of a premature stop codon. Knockout of the BmGC-I gene resulted in the q-like abnormal pigmentation, thereby demonstrating that the BmGC-I gene is involved in the pigment biosynthesis pathway in the integument. Moreover, quantitative reverse transcription polymerase chain reaction showed that BmGC-I was strongly expressed in the fourth instar on day 2. Our results suggest that BmGC-I deficiency affects the pigment biosynthesis pathway, which supports the involvement of guanylyl cyclase in larval coloration.
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Affiliation(s)
- Masashi Yuasa
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Takashi Kiuchi
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Yutaka Banno
- Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, Fukuoka, Japan
| | - Susumu Katsuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Toru Shimada
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
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Abstract
The thermoprotective mechanisms of insects remain largely unknown. We reported the Bombyx mori contractile (cot) behavioral mutant with thermo-sensitive seizures phenotype. At elevated temperatures, the cot mutant exhibit seizures associated with strong contractions, rolling, vomiting, and a temporary lack of movement. We narrowed a region containing cot to ~268 kb by positional cloning and identified the mutant gene as Bmsei which encoded a potassium channel protein. Bmsei was present in both the cell membrane and cytoplasm in wild-type ganglia but faint in cot. Furthermore, Bmsei was markedly decreased upon high temperature treatment in cot mutant. With the RNAi method and injecting potassium channel blockers, the wild type silkworm was induced the cot phenotype. These results demonstrated that Bmsei was responsible for the cot mutant phenotype and played an important role in thermoprotection in silkworm. Meanwhile, comparative proteomic approach was used to investigate the proteomic differences. The results showed that the protein of Hsp-1 and Tn1 were significantly decreased and increased on protein level in cot mutant after thermo-stimulus, respectively. Our data provide insights into the mechanism of thermoprotection in insect. As cot phenotype closely resembles human epilepsy, cot might be a potential model for the mechanism of epilepsy in future.
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Mun S, Noh MY, Osanai-Futahashi M, Muthukrishnan S, Kramer KJ, Arakane Y. A Major Facilitator Superfamily protein encoded by TcMucK gene is not required for cuticle pigmentation, growth and development in Tribolium castaneum. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2014; 49:43-48. [PMID: 24681434 DOI: 10.1016/j.ibmb.2014.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 03/01/2014] [Accepted: 03/14/2014] [Indexed: 06/03/2023]
Abstract
Insect cuticle pigmentation and sclerotization (tanning) are vital physiological processes for insect growth, development and survival. We have previously identified several colorless precursor molecules as well as enzymes involved in their biosynthesis and processing to yield the mature intensely colored body cuticle pigments. A recent study indicated that the Bombyx mori (silkmoth) gene, BmMucK, which encodes a protein orthologous to a Culex pipiens quiquefasciatus (Southern house mosquito) cis,cis, muconate transporter, is a member of the "Major Facilitator Superfamily" (MFS) of transporter proteins and is associated with the appearance of pigmented body segments of naturally occurring body color mutants of B. mori. While RNA interference of the BmMucK gene failed to result in any observable phenotype, RNAi using a dsRNA for an orthologous gene from the red flour beetle, Tribolium castaneum, was reported to result in molting defects and darkening of the cuticle and some body parts, leading to the suggestion that orthologs of MucK genes may differ in their functions among insects. To verify the role and essentiality of the ortholog of this gene in development and body pigmentation function in T. castaneum we obtained cDNAs for the orthologous gene (TcMucK) from RNA isolated from the GA-1 wild-type strain of T. castaneum. The sequence of a 1524 nucleotides-long cDNA for TcMucK which encodes the putatively full-length protein, was assembled from two overlapping RT-PCR fragments and the expression profile of this gene during development was analyzed by real-time PCR. This cDNA encodes a 55.8 kDa protein consisting of 507 amino acid residues and includes 11 putative transmembrane segments. Transcripts of TcMucK were detected throughout all of the developmental stages analyzed. The function of this gene was explored by injection of two different double-stranded RNAs targeting different regions of the TcMucK gene (dsTcMucKs) into young larvae to down-regulate transcripts during subsequent stages of insect development until the adult stage. RNA interference of TcMucK had no observable effects on larval, pupal or adult pigmentation. In addition, it did not affect larval-larval, larval-pupal and pupal-adult molting or survival. Thus, in contrast to the results of Zhao et al. (2012), our study demonstrates that TcMucK is not essential for growth, development or cuticle pigmentation of T. castaneum.
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Affiliation(s)
- Seulgi Mun
- Department of Applied Biology, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea
| | - Mi Young Noh
- Department of Applied Biology, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea
| | - Mizuko Osanai-Futahashi
- Transgenic Silkworm Research Unit, National Institute of Agrobiological Sciences (NIAS), Tsukuba, Ibaraki 305-8634, Japan
| | - Subbaratnam Muthukrishnan
- Department of Biochemistry and Molecular Biophysics, Kansas State University, 141 Chalmers Hall, Manhattan, KS 66506, USA
| | - Karl J Kramer
- Department of Biochemistry and Molecular Biophysics, Kansas State University, 141 Chalmers Hall, Manhattan, KS 66506, USA
| | - Yasuyuki Arakane
- Department of Applied Biology, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea.
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